Vehicle operation system and method

ABSTRACT

A method of operating a vehicle having an engine, an engine control unit (ECU), a throttle operator, and a throttle body fluidly communicating with the engine. A throttle valve disposed in the throttle body regulates fluid flow to the engine. A throttle valve actuator is connected thereto for controlling a throttle valve position. A key receiver is configured to link to a key. The method includes linking a key to the key receiver and initiating engine operation. If the key is linked to the key receiver and engine operation has been initiated, an identification code of the key is read and an authorization status of the key is thereby determined. If the key is determined to be authorized, the throttle valve position is controlled based in part on a throttle operator position. If the key is determined to be unauthorized, the throttle valve position is limited to a security limit.

CROSS-REFERENCE

The present application is a continuation-in-part of InternationalPatent Application No. PCT/US2013/48803, filed Jun. 29, 2013, whichclaims priority to U.S. Provisional Patent Application No. 61/666,443filed on Jun. 29, 2012, U.S. Provisional Patent Application No.61/758,322 filed on Jan. 30, 2013, and U.S. Provisional PatentApplication No. 61/768,285 filed on Feb. 22, 2013, the entirety of allof which is incorporated herein by reference.

TECHNICAL FIELD

The present technology relates to systems and methods for operatingvehicles.

BACKGROUND

Snowmobiles and other vehicles used for recreational purposes such asall-terrain vehicles (ATVs), personal watercraft and the like have athrottle operator, such as a throttle pedal or a throttle lever forcontrolling vehicle speed and/or engine power output. The throttle leveris pivotally mounted to the handlebar so that it pivots towards and awayfrom the handlebar in response to the driver's pushing or releasing ofthe throttle lever to increase or decrease speed of the vehicle.Similarly, the throttle pedal is pivotably mounted to the vehicle frameon a vehicle floor so as to be accessible by the driver's foot, thepedal being pushed towards the floor to increase the vehicle speed orengine output power. In conventional vehicles, the throttle operator isconnected by a mechanical linkage to the throttle valve which regulatesair flow to the engine in a fuel-injection engine or fuel intake in acarbureted engine. The degree of opening of the throttle valve directlycorresponds to the position of the throttle lever. The air flow to theengine determines the power output by the engine, and therefore theperformance of the vehicle. In some situations, it is desirable tocontrol the opening of the throttle valve based not only on the positionof the throttle operator but on other factors such as the current ordesired engine speed (i.e. rotational speed of an output shaft of theengine), fuel economy, noise emission and the like.

SUMMARY

It is an object of the present technology to ameliorate at least some ofthe inconveniences present in the prior art.

In an aspect of the present technology, a vehicle includes an engine, anengine control unit (ECU) controlling operation of the engine, athrottle operator operatively connected to the ECU, a throttle bodyfluidly communicating with the engine, a throttle valve disposed in thethrottle body regulating fluid flow to the engine, a throttle valveactuator connected to the throttle valve for controlling a throttlevalve position, the throttle valve actuator being in electroniccommunication with the ECU, and a key receiver configured to link to akey. The method of operating the vehicle includes linking a key to thekey receiver, and initiating engine operation. If the key is linked tothe key receiver and engine operation has been initiated: anidentification code of the key is read and thereby an authorizationstatus of the key determining. If the key is determined to be anauthorized key, the throttle valve position is controlled based in parton a throttle operator position. If the key is determined to be anunauthorized key, the throttle valve position is limited to be less thana security limited throttle valve position.

In a further aspect, the security limited throttle valve positioncorresponds to a closed position of the throttle valve.

In a further aspect, the security limited throttle valve positioncorresponds to an idle operation engine speed.

In another aspect, the security limited throttle valve position is lessthan a CVT engagement position of the throttle valve.

In yet another aspect, the step of reading the digitally encodedidentification of the digitally encoded key occurs when an engine speedis greater than a transponder threshold engine speed, the transponderthreshold engine speed being less than a CVT engagement speed.

In an additional aspect, the engine is deactivated if the key isdetermined to be an unauthorized key.

In an additional aspect, an indication of authorization failure isprovided if the key is determined to be an unauthorized key.

In a further aspect, the vehicle has an engine cut-off switch. Themethod further includes preventing engine operation if the enginecut-off switch is activated.

In an additional aspect, the vehicle has a switch electrically connectedto the key receiver. The switch is closed when a key is coupled to thekey receiver. Engine operation is prevented if the switch is not closed.

In another aspect, the switch is a reed switch.

In another aspect, the vehicle further has an engine start-up switch andthe step of initiating engine operation is performed by actuating theengine start-up switch to an on position.

In a further aspect, the vehicle has a starter rope connected to acrankshaft of the engine for starting rotation thereof, and the step ofinitiating engine operation is performed by pulling the starter rope.

In yet another aspect, the method includes determining one of thethrottle operator position and the throttle valve position, andpreventing connection between a battery and a starter motor if the oneof the throttle operator position and the throttle valve position isgreater than the corresponding one of a throttle operator limit positionor a throttle valve position limit.

In a further aspect, the method includes activating the ECU, andlimiting the throttle valve position to a first limit throttle valveposition if the engine speed is less than a first threshold engine speedand at least a first threshold time period has lapsed after activationof the ECU. The ECU and the throttle valve actuator are deactivated ifthe engine speed is less than a second threshold engine speed and atleast a second threshold time period has lapsed after activation of theECU. The second threshold time period is greater than the firstthreshold time period. The first threshold engine speed is less than aCVT engagement engine speed, and the second threshold engine speed isless than the CVT engagement engine speed.

In an additional aspect, the first threshold engine speed is equal tothe second threshold engine speed.

In an additional aspect, the first limit throttle valve position is oneof greater than and equal to the security limited throttle valveposition.

In another aspect, the first limit throttle valve position correspondsto a closed position of the throttle valve.

In yet another aspect, the first limit throttle valve positioncorresponds to an idle operation engine speed.

In an additional aspect, the first limit throttle valve positioncorresponds to an engine speed that is less than a CVT engagement enginespeed.

In another aspect, the vehicle comprises a transponder to read theidentification code, and the step of reading the identification codeoccurs when an engine speed is greater than a transponder thresholdengine speed, the transponder threshold engine speed being less than aCVT engagement speed.

In a further aspect, the first threshold engine speed is smaller thanthe transponder threshold engine speed.

In an additional aspect, the present provides a method of operating avehicle. The vehicle has an engine, an engine control unit (ECU)controlling operation of the engine, a throttle operator operativelyconnected to the ECU, a throttle body fluidly communicating with theengine, a throttle valve disposed in the throttle body regulating fluidflow to the engine, a throttle valve actuator connected to the throttlevalve for controlling a throttle valve position, the throttle valveactuator being in electronic communication with the ECU, and a keyreceiver configured to couple to a key. The method includes lining adigitally encoded key with the key receiver. If a digitally encoded keyis installed in the key receiver, the throttle valve position is limitedto a first limit throttle valve position if the engine speed is lessthan a first threshold engine speed at a time at least equal to a firstthreshold time.

In another aspect, the throttle valve actuator is deactivated if theengine speed is less than the second threshold engine speed at a time atleast equal to a second threshold time, the second threshold time beinggreater than the first threshold time.

In yet another aspect, the first threshold engine speed is equal to thesecond threshold engine speed.

In an additional aspect, the first limit throttle valve positioncorresponds to a fully closed position of the throttle valve.

In another aspect, the first limit throttle valve position correspondsto an idle operation engine speed.

In another aspect, the first limit throttle valve position correspondsto an engine speed that is less than a CVT engagement engine speed.

In yet another aspect, limiting the throttle valve to a first limitthrottle valve position includes opening an electric circuit connectedto the throttle valve actuator.

In a further aspect, a vehicle has a frame. An engine is connected tothe frame and has a rotatable crankshaft. An engine speed is defined bya rotational speed of the crankshaft. An engine control unit (ECU) isoperatively connected to the engine for controlling the operation of theengine. A throttle body fluidly communicates with the engine. A throttlevalve is disposed in the throttle body for regulating fluid flow to theengine, the throttle valve being movable between a closed position andan open position. A throttle valve actuator is connected to the throttlevalve for controlling a throttle valve position for regulating fluidflow through the throttle body into the engine, the throttle valveactuator being in electronic communication with the ECU. A throttleoperator is connected to the frame and operatively connected to at leastone of the ECU and the throttle valve actuator. An engine cut-off switchis in electronic communication with the ECU and configured to preventengine operation when activated. A key receiver is configured to belinked to a key and a reed switch is electrically connected to keyreceiver, the reed switch being configured to be closed when the key islinked to the key receiver. The ECU is configured to read anidentification code of a key linked to the key receiver to determine anauthorization status of the key. The throttle valve position is lessthan security limited throttle valve position if the key is anunauthorized key. The throttle valve position is based on a throttleoperator position if the key is an authorized key. The throttle valveposition is a first limit throttle valve position if the engine speed isless than a threshold engine speed and an ECU timer value is at leastequal to a threshold time.

In another aspect of the present technology, a method of operating avehicle is provided. The vehicle has an engine for generating electricalpower, an engine control unit (ECU) operatively connected to the enginefor controlling operation of the engine, a throttle operator operativelyconnected to the ECU, a throttle body fluidly communicating with theengine, a throttle valve disposed in the throttle body regulating fluidflow to the engine, and a key receiver connected to the ECU andconfigured to receive a digitally encoded key. The method comprises:installing a digitally encoded key to the key receiver; detecting apresence of the key without reading an identification code of the key;providing an electrical power to the key receiver; and reading anidentification code of the key with the key receiver responsive to thekey receiver receiving the electrical power.

In another aspect, the key receiver is configured to receive power onlyif the key is installed thereto; and detecting of the presence of thekey is achieved by determining that the key receiver has received power.

In another aspect, the key receiver comprises a sensor and a reader; theelectrical power comprises a first electrical power and a secondelectrical power, the second electrical power being greater than thefirst electrical power; the presence of the key is detected by thesensor without reading the identification code of the key and responsiveto the sensor receiving the first electrical power; the identificationcode of the key is read by the reader responsive to the reader receivingthe second electrical power.

In another aspect, the key comprises a magnetic member; and the sensorcomprises a hall effect sensor configured to sense a magnetic field ofthe magnetic member for detecting the presence of the key.

In another aspect, the key comprises an RFID tag; and the readercomprises an RFID reader configured to obtain the identification code ofthe key via radiofrequency communication with the RFID tag.

In another aspect, the engine also has a crankshaft, the enginegenerating power when the crankshaft rotates; a magneto connected to thecrankshaft for rotation therewith; and a rope connected to thecrankshaft for manual start up of the engine, the crankshaft and themagneto being rotated by the rope when pulling on the rope. The methodalso comprises: generating the first electrical power by pulling therope to rotate the crankshaft and the magneto; and providing, to thesensor, the first electrical power generated by the engine as a resultof the pulling of the rope.

In another aspect, the snowmobile further also has a fuel injectionsystem fluidly connected to the engine; and an ignition system connectedto the engine. The method further comprises, before providing the secondelectrical power to the reader: operating the fuel injection system toinject fuel into the engine; operating the ignition system to ignite thefuel injected into the engine; and increasing a rotational speed of thecrankshaft responsive to the igniting of the fuel injected into theengine.

In another aspect, the identification code of the key is read by thereader responsive to the rotational speed of the crankshaft beinggreater than a reader threshold engine speed.

In another aspect, the snowmobile comprises a CVT operatively connectedto the crankshaft; and the reader threshold engine speed is smaller thana CVT engagement speed.

In another aspect, the method also comprises: determining anauthorization status of the read identification code of the key; andresponsive to the identification code of the key being determined tohave an authorized status, controlling the throttle valve position basedat least in part on a throttle operator position.

In another aspect, the method also comprises, responsive to theidentification code of the key being determined to have an unauthorizedstatus, limiting the engine speed to a security limited engine speed.

In another aspect, the security limited engine speed is lower than theCVT engagement speed.

In another aspect, the rope is pulled only once prior to reading theidentification code of the key. For purposes of the present application,terms related to spatial orientation when referring to a vehicle andcomponents in relation to the vehicle, such as “forwardly”,“rearwardly”, “left”, “right”, “above” and “below”, are as they would beunderstood by a driver of the vehicle, with the vehicle in a straightahead orientation (i.e. not steered left or right), and in an uprightposition (i.e. not tilted). The definitions provided herein takeprecedence over the definitions that may be provided in the documentsincorporated herein by reference.

Implementations of the present technology each have at least one of theabove-mentioned object and/or aspects, but do not necessarily have allof them. It should be understood that some aspects of the presenttechnology that have resulted from attempting to attain theabove-mentioned object may not satisfy this object and/or may satisfyother objects not specifically recited herein.

Additional and/or alternative features, aspects, and advantages ofimplementations of the present technology will become apparent from thefollowing description, the accompanying drawings, and the appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present technology, as well as otheraspects and further features thereof, reference is made to the followingdescription which is to be used in conjunction with the accompanyingdrawings, where:

FIG. 1 is a right side elevation view of a snowmobile;

FIG. 2 is a top plan view of the handlebar of the snowmobile of FIG. 1;

FIG. 3A is a perspective view, taken from a rear, right side, of aportion of the snowmobile of FIG. 1 showing a security system;

FIG. 3B is a left side elevation view of a key of the security system ofFIG. 3A;

3C is a schematic illustration of a circuit of the security system ofFIG. 3A;

FIG. 4 is a schematic illustration of an air intake system connected toan engine control unit and a throttle control module of the snowmobileof FIG. 1;

FIG. 5A is a side elevation view of a throttle body and a throttle valveactuator of the air intake system;

FIG. 5B is a perspective view of the throttle body and throttle valveactuator of FIG. 5A with a throttle valve disposed in a closed position;

FIG. 5C is a perspective view of the throttle body and throttle valveactuator of FIG. 5A with a throttle valve disposed in an open position;

FIG. 6 is a schematic illustration of elements of the engine controlunit of the snowmobile of FIG. 1;

FIG. 7 is a left side elevation view of a portion of the snowmobile ofFIG. 1 showing a portion of the frame, the engine, the CVT, and othercomponents connected thereto;

FIG. 8 is a left side elevation view of a portion of the snowmobile ofFIG. 1 with the CVT removed for clarity;

FIG. 9 is a perspective view of a portion of the snowmobile of FIG. 1;

FIG. 10 is a top plan view of a portion of the snowmobile of FIG. 1;

FIG. 11 is a top plan view of the snowmobile portion of the FIG. 10 withthe seat and fuel tank removed for clarity;

FIG. 12 is a rear elevation view of the snowmobile portion of the FIG.11;

FIG. 13 is a left side elevation view of the snowmobile portion of theFIG. 10;

FIG. 14 is a right side elevation view of the snowmobile portion of theFIG. 10;

FIG. 15 is a right side elevation view of the snowmobile portion of theFIG. 14 with the seat and fuel tank removed for clarity;

FIG. 16A is a logic diagram illustrating a method of controllingoperation of the snowmobile of FIG. 1; and

FIG. 16B is a continuation of the logic diagram of FIG. 16A;

FIG. 17 is a schematic illustration of another implementation of asecurity system;

FIG. 18 is a graphical representation of various electrical signals as afunction of time during start-up of the vehicle using the securitysystem of FIG. 17; and

FIG. 19 is a logic diagram illustrating another implementation of amethod of controlling operation of the snowmobile.

DETAILED DESCRIPTION

Although a snowmobile is being described herein, it should be understoodthat aspects of the present technology could also be applied to otherkinds of vehicles such as, for example, all-terrain vehicles (ATV),motorcycles, three-wheeled motorized vehicles, and personal watercraft.

Referring to FIG. 1, a snowmobile 10 includes a forward end 12 and arearward end 14 which are defined consistently with a travel directionof the vehicle. The snowmobile 10 includes a vehicle body in the form ofa frame or chassis 18 which includes a tunnel 22, an engine supportstructure 24, a front suspension module 21, and an upper structure 23(FIG. 7). A longitudinal centerplane 13 (longitudinally disposedvertical plane) is defined by the frame 18 (FIG. 10).

Two skis 16 positioned at the forward end 12 of the snowmobile 10 areattached to the frame 18 by a front suspension assembly 20. The frontsuspension assembly 20 includes ski legs, supporting arms and balljoints (not shown) for operatively joining the respective ski legs,supporting arms and a steering column 42. The front suspension assembly20 and skis 16 are connected by a front suspension module 21 to thefront end of the engine compartment 24 as can be seen in FIG. 7.

An the engine support structure 24. An engine 26 (illustratedschematically in FIG. 1), is carried in an engine compartment defined bythe engine support structure 24 of the frame 18. An engine control unit(ECU) 200 is operatively connected to the engine 26 for controllingoperation of the engine 26 as will be discussed below in further detail.A battery 144 (FIG. 3C) is also provided to power vehicle systems suchas the ECU 200, a starter motor 43, the throttle valve actuator 74 (FIG.5A), and the like, before the engine 26 is operating at an engine speedthat is great enough to generate enough power for these functions.

An endless drive track 28 is positioned at the rear end 14 of thesnowmobile 10. The drive track 28 is disposed generally under the tunnel22, and operatively connected to the engine 26 via a belt transmissionsystem 50 (illustrated schematically by broken lines in FIG. 1). Theendless drive track 28 is driven to run about a rear suspension assembly29 for propulsion of the snowmobile 10. The rear suspension assembly 29includes a drive sprocket 31, one or more idler wheels and a pair ofslide rails in sliding contact with the endless drive track 28. Thedrive sprocket defines a sprocket axis 31 a (FIG. 7). The slide railsare attached to the tunnel 22 by front and rear suspension arms and oneor more shock absorbers which may further include a coil spring (notshown) surrounding the individual shock absorbers.

At the front end 12 of the snowmobile 10, fairings 30 enclose the engine26 and the belt transmission system 50, thereby providing an externalshell that not only protects the engine 26 and the belt transmissionsystem 50, but can also be decorated to make the snowmobile 10 moreaesthetically pleasing. Typically, the fairings 30 include a hood (notindicated) and one or more side panels which can be opened to allowaccess to the engine 26 and the belt transmission system 50 when this isrequired, for example, for inspection or maintenance of the engine 26and/or the belt transmission system 50. A windshield connected to thefairings 30 acts as a wind screen to lessen the force of the air on therider while the snowmobile 10 is moving.

A fuel tank 58, supported above the tunnel 22, supplies fuel to theengine 26 for its operation. Fuel is collected in the fuel tank 58 via afiller tube 59 (FIG. 7) disposed on an upper surface of the fuel tank58. The filler tube 59 is formed in a portion of the fuel tank 58extending upwardly and forwardly from the tunnel 22.

A straddle-type seat 32 is positioned atop the fuel tank 58 toaccommodate a driver of the snowmobile 10. The lower surface of the seat32 is positioned on the fuel tank 58. The front portion of the uppersurface of the fuel tank 58 extends forwardly and upwardly from theupper surface 38 of the seat 32. The seat 32 has left and right lateralsurfaces 37 extending downwardly from the upper seat surface 38. A rearportion of the seat 32 may include a storage compartment or can be usedto accommodate a passenger seat (not indicated). A footrest 34 ispositioned on each side of the snowmobile 10 below the seat 32 toaccommodate the driver's feet.

A display cluster 48 is provided in front of the seat 32 to displayinformation, such as the vehicle speed, engine speed, vehicle mode,temperature and the like, to the driver of the snowmobile 10. Thedisplay cluster 48 possibly includes one or more gauges, displayscreens, indicator lights and sound output devices such as speakers,alarms and the like.

With reference to FIGS. 9 and 10, the upper structure 23 comprises aleft and right forward braces 23 a and left and right rearward braces 23b. The braces 23 a, 23 b interconnect together at a junction 23 c abovethe engine compartment 24 to form a pyramidal structure. The forwardbraces 23 a extend downwardly, forwardly and laterally outwardly fromthe junction 23 c to the corresponding left or right front corner of thefront suspension module 21. A lateral support brace 25 connects betweenthe bottom ends of the forward braces 23 a. A front suspension modulebracket 21 a is attached to the bottom end of each forward support brace23 a and to the front suspension module 21 to distribute force from thefront suspension 20 to other areas of the snowmobile 10. Each rearwardbrace 23 b extends downwardly, rearwardly and laterally outwardly fromthe junction 23 c to the tunnel 22.

With reference to FIG. 11, the right braces 23 a and 23 b form a firstimaginary face of the pyramidal structure 23 d. The rear braces 23 bform a second imaginary face of the pyramidal structure 23 d. The leftbraces 23 a and 23 b form a third imaginary face of the pyramidalstructure 23 d. The front braces 23 a form a fourth imaginary wall ofthe pyramidal structure 23 d. The four imaginary faces forming thepyramidal structure 23 d overlay several components within the enginecompartment 24 including the throttle body 68, throttle valve 70,throttle valve actuator 74 and throttle valve sensor 72.

A steering assembly 36, including a handlebar 37 and a steering column42, is provided generally forward of the seat 32. The steering column 42is connected to the frame 18. The handlebar 37 is attached to the upperend of the steering column 42. The steering column 42 is connected tothe upper structure 23 and disposed laterally between the forward braces23 a. The upper end of the steering column 42, extending above thejunction 23 c of the upper structure 23 has the handlebar 37 attachedthereto. The handlebar 37 extends generally laterally outwardly from thesteering column 42. The handlebar 37 is used to rotate the skis 16, inorder to steer the vehicle 10. A left hand grip 38 and a right hand grip40 are provided on the handlebar 37 to facilitate gripping.

With reference to FIG. 2, a throttle control module 100 is provided onthe right side of the handlebar 37. The throttle control module 100 isconnected to the ECU 200. The throttle control module 100 includes athrottle operator 44 in the form of a finger-actuated throttle lever 44mounted to adjacent the right handgrip of the handlebar 37. Other typesof throttle operators, such as a thumb-actuated throttle lever and atwist grip, are also contemplated. The throttle lever 44 is normallybiased, typically by a spring, towards a position furthest away from thehandlebar 37. This position of the throttle lever 44 is indicative of adesire for an idle operation of the engine 26. The throttle lever 44 canbe pressed towards the handlebar 37 to increase air flow into the engine26, and to thereby increase the output power of the engine 26 by meansof a throttle-by-wire (TBW) system. U.S. Provisional Patent ApplicationNo. 61/666,443, filed on Jun. 29, 2012, the entirety of which isincorporated herein by reference, provides additional details of suchthrottle systems in vehicles. The throttle control module 100 alsoincludes a throttle operator position sensor 204 connected to thethrottle lever 44 for sensing the position of the throttle lever 44. Athrottle operator position PP is defined as a fraction of its fullyactivated position (when throttle lever 37 is at its closest position tothe handlebar 36). The throttle operator position PP thus varies between0% (unactivated or idle position) and 100% (fully activated or “drive”position).

The snowmobile 10 also includes an engine cut-off switch 116. The enginecut-off switch 116 is a push-pull button switch connected to the ECU 200for turning off the engine 26. The engine cut-off switch 116, extendsupwards from the right side of the handlebar 37. The position of theengine cut-off switch 116 close to the right hand grip 40 enables thesnowmobile driver to easily reach the engine cut-off switch 116 and tooperate it to stop engine operations. The ECU 200 may terminate engineoperation by preventing current flow to either the fuel pump or the fuelinjectors to deprive the engine 26 of fuel, or it may stop current flowto the spark plugs to prevent fuel combustion in the engine 26. It isalso contemplated that the ECU 200 may use two or more of these methodsconcurrently to stop snowmobile motion and/or engine operation. Othermethods of preventing movement of the snowmobile 10 may be apparent to aperson skilled in the art, and any of these other methods are consideredto be within the scope of the present technology.

A brake actuator 46, in the form of a hand brake lever 46, is providedon the handlebar 37 for braking the snowmobile 10 in a known manner. Thebrake actuator 46 is placed adjacent to the left hand grip 38 on theleft side of the handlebar 37.

A start-up switch 120, in the form of a push-button, is located on theleft side of the handlebar 37 near the brake lever 46. The driverindicates a desire to start-up the engine 26 by actuating the start-upswitch 120, i.e. by pushing the start-up switch 120 to an “ON” position.In the illustrated implementation of the snowmobile 10 with a startermotor 43 for starting the engine 26. The starter motor 43, whenactivated, selectively engages a flywheel connected to a crankshaft (notshown) of the engine 26 and thereby rotates the crankshaft to start theengine 26. It is contemplated that the starter motor 43 could be omittedand a starter cord or rope 122 could be connected to the flywheel torotate the crankshaft and start operation of the engine 26. Thus,instead of pushing a button, the driver could pull a rope 122 tostart-up the engine 26 as discussed in the implementation of FIGS. 17 to19.

With reference to FIGS. 3A to 3C, the snowmobile 10 is provided with asecurity system 130 such as, for example, Bombardier RecreationProduct's Digitally Encoded Security System (DESS™). The security system130 includes a key receiver 132 and a key 134 tied to a lanyard 136. Thekey receiver 132 is in the form of a metal cylinder positioned in frontof the seat 32 on the right side of the upper end of the steering column42 and below the right side handlebar 37. The cup-shaped key 134 fitsover the key receiver 132. The key 134 includes a magnet and a digitallyencoded chip containing identification information.

The key receiver 132 comprises a reed switch 138 which can be actuatedby a magnetic field. When the key 134 is installed on the key receiver132, the magnet in the key 134 closes the reed switch 138. When the key134 is removed from the key receiver 132, the magnetic field due to thekey magnet is removed, resulting in the reed switch 138 becoming open.The reed switch 138 is part of a security system circuit 140 which iscompleted when the reed switch 138 is closed. The security systemcircuit 140 further includes a security system transponder 142 and abattery 144. When the reed switch 138 is closed, the battery 144 isconnected to the security system transponder 142. The transponder 142 isthus activated for receiving and sending signals. The security systemtransponder 142 communicates with the linked digitally encoded key 134and the ECU 200.

The transponder 142 requests and receives the encoded identificationinformation from the key 134. The transponder 142 transmits the encodedidentification information to the ECU 200. The ECU 200 decodes theidentification information and compares the identification informationof the security system key 134 with a database of authorizedidentification codes to determine whether the security system key 134 isauthorized for operating the snowmobile 10. The database ofidentification codes is previously stored in a memory of the ECU 200. Itis also contemplated that the transponder 142 decodes the identificationinformation. It is further contemplated that the authorization status ofthe key 134 is verified by the transponder 142, which then transmits theauthorization status to the ECU 200. The database of authorizedidentification codes could additionally be stored in a memory of thesecurity system transponder 142, or the transponder 142 could access thedatabase from the ECU 200.

It should be understood that the security system 130 having a magneticcup-shaped key 134 and complementary key receiver 132 with a reed switch138 described above is only meant to be exemplary. Other systems forverifying authorization are also contemplated. For example, the key 134could be in the form of a ring or a card having encoded identificationinformation. The identification codes could be stored in areas of thekey 134 that are magnetically/electrically/optically sensitive andcapable of communicating with complementary areas of a key receiver 132.The key 134 could be inserted into, swiped, waved or otherwise broughtin proximity of the key receiver 132. The identification code of the key134 could be read by a transponder 142 when in proximity thereto withoutrequiring contact. The key 134 could also be similar to a conventionalmechanical key have physical features such as a surface, edge,protrusions and the like, and the key receiver 132 could havespring-loaded portions actuated via mechanical contact (or lack thereof)when the key 134 is inserted or otherwise coupled thereto. Thus, theterm “key” as used herein is meant to encompass any element havingidentifiable or distinguishable features, including a digitalidentification code. The term “identification” referred to herein isintended to broadly encompass any distinguishing characteristic of a“key”. The term “key receiver” as used herein is intended to encompass asecond element that can be linked to the first element (“key”) in such away as to be able to distinguish at least one of a plurality of “keys”.

The key receiver 134 is able to read the identification of the key 134when the key 134 and the key receiver 132 are linked to each other. Theterm “read” is intended to encompass any means of sensing, detecting ordistinguishing an identification feature of the key. The link betweenthe key receiver 132 and the key 134 could be via physical contact, suchas a mechanical contact or an electrical connection. The link could alsobe established without any physical contact. For example, the link couldbe a wireless link by means of electromagnetic, optical orradio-frequency communication, and the like. In the illustratedimplementation, the key 134 is linked to the key receiver 134 byinstalling or placing the key 134 over the key receiver 134

With reference to FIGS. 3A and 3B, a lanyard 136 attached to an end ofthe key 134 is intended to be clipped to the driver of the snowmobile10. If the snowmobile driver leaves the snowmobile 10, the key 134fastened to the snowmobile driver by the lanyard 136, disengages fromthe key receiver 132. The engine 26 and other systems are deactivatedwhen the security system key 134 is removed from the key receiver 132.The security system 130 thus also serves as a safety system for thesnowmobile 10 terminating operation of the snowmobile 10 if thesnowmobile driver is separated from the snowmobile 10 during operation.

Thus, the engine 26 and other systems of the snowmobile can be turned onor activated only if the key 134 is coupled to, or installed on, the keyreceiver 132. The engine 26 is operable only when an authorized securitysystem key 134 is installed on the key receiver 132, the engine cut-offswitch 116 is an “OFF” position or deactivated, and the start-up switch120 is in an “ON” position. Various methods for starting up thesnowmobile 10 will be discussed below in further detail.

With reference to FIGS. 7 and 8, the engine 26 drives an engine outputshaft 54 that rotates about a horizontally disposed axis extendinggenerally transversely to a longitudinal centerplane 13 of thesnowmobile 10. In the present implementation, the output shaft 54 is acrankshaft of the engine 26. However, it is contemplated that thecrankshaft and the output shaft 54 could be separate shaft connected toeach other such that the crankshaft drives the output shaft 54. Theengine output shaft 54 drives the transmission system 50 fortransmitting torque to the endless drive track 28 for propulsion of thesnowmobile 10. The transmission 50 (shown in FIG. 7, removed for clarityin FIG. 8) is connected to the drive sprocket 31 and rear track 28 via areduction gear 57. The transmission 50 is disposed on the left side ofthe engine 26. The reduction gear 57 is disposed on the right side ofthe snowmobile 10. The transmission 50 is a continuously variabletransmission (CVT) comprising a variable diameter drive pulley 51coupled to a variable diameter driven pulley 52 by a belt 53. It iscontemplated that other kinds of transmissions could also be used. Theoutput shaft 54 of the engine 26 is connected to the drive pulley 51 ofthe CVT 50. The countershaft 55 of the CVT 50 is connected to thereduction gear 57, and thereby to the front drive axle 56 of the drivesprocket 31. The drive pulley 51 and the output shaft 54 rotate at anengine speed ES about a drive pulley rotation axis 51 a. The drivenpulley 52 and the countershaft 55 rotate about a drive pulley rotationaxis 52 a at a speed determined in accordance with the instantaneousratio of the CVT 50. A CVT plane 50 a is defined by the rotation axes 51a, 52 a of the CVT pulleys 51, 52.

Each of the pulleys 51, 52 includes a movable sheave that can moveaxially relative to a fixed sheave to modify an effective diameter ofthe corresponding pulley 51, 52. The drive pulley 51 sheaves are biasedaway from each other so that when not rotating, the drive pulley sheavesare far apart and the belt 53 is disengaged from the drive pulley 51.The moveable sheave moves in response to changes in engine speed ES. Theeffective diameters of the pulleys 51, 52 are in inverse relationship.In the illustrated implementation, the CVT 50 is a purely mechanical CVT50, in which the effective diameter of the drive pulley 52 depends onthe engine speed ES and torque applied to the track 28. As the engineoutput shaft 54 and the drive pulley sheaves begin to rotate withincreasing rotational speeds ES, the separation between the drive pulleysheaves decreases due to the action of a set of centrifugal weightspushing the moveable sheave towards the fixed sheave. At a certainengine speed ES, the drive pulley sheaves engage the belt 53 which inturn begins to rotate the driven pulley sheaves. The rotational speed ES(of the engine output shaft 54 and drive pulley sheaves 51) at which thedrive pulley sheaves engage the belt 53 is referred to as the engagementspeed ES_(engage). It is also contemplated that the CVT 50 could be anassisted CVT having a hydraulic, pneumatic, or other system to controlthe effective diameter of the pulleys 51 or 52, and thus, the engagementspeed ES_(engage) of the CVT 50.

For rotational speeds ES greater than the engagement speed ES_(engage),the engine 26 is operatively connected via the CVT 50 to the track 28.For rotational speeds ES less than the engagement speed ES_(engage), theCVT 50 is not engaged and thus the powertrain 75 cannot deliver torqueand power from the engine 26 to the tracks 28. The snowmobile 10 is thusnot being driven by the engine 26, and the engine 26 is in idleoperation for engine speeds ES less than the engagement speedES_(engage). Idle operation of the engine 26 enables powering of vehiclesystems such as the displays 48, the ECU 200, and the like. The engine26 can be placed in idle operation by releasing the throttle lever 44without turning off the engine 26.

The engine 26 is an inline, three-cylinder, four-stroke, internalcombustion engine. The cylinders are aligned with their cylindrical axesdisposed vertically. A cylindrical plane 27 is formed by the parallelcylindrical axes of the cylinders. It is contemplated that the enginecould be configured differently. For example, the engine 26 could havemore or less than three cylinders, and the cylinders could be arrangedin a V-configurations instead of in-line. It is contemplated that theengine 26 could be a two-stroke internal combustion engine, a carburetedengine, or any other suitable engine or motor capable of propelling ofthe snowmobile 10.

The engine 26 receives fuel from the fuel tank 58 via a fuel injectionsystem 80. (FIG. 6). The engine 26 receives air from an air intakesystem 60. The air intake system 60 is connected to an air inlet 61(FIG. 14) defined in the rear portion of the engine 26. The fuel-airmixture in the engine 26 is ignited by an ignition system 82. Exhaustgases resulting from the combustion process are expelled from the engine26 via an exhaust system 90. Engine output power P, torque τ and enginespeed ES are determined in part by the fuel-air mixture in the engine 26and the ignition timing IT. An engine control unit (ECU) 200 isoperatively connected to the engine 26 to control operation of theengine 26 as will be discussed below.

With reference to FIGS. 13 and 14, an exhaust outlet 94 is defined inthe front portion of the engine 26. The exhaust system 90 includes anexhaust conduit 92 which is connected to the exhaust outlet 94 andextends forwardly therefrom to direct exhaust gases out of the engine.The air inlet 61 is disposed on the side opposite the exhaust outlet 94.

The air intake system 60, best seen in FIGS. 8, 14 and 15, includes aprimary airbox 66, a throttle body 68 and a secondary airbox 62. Airenters the secondary airbox 62 through an inlet 64 in the front portionof the snowmobile 10. The air is then directed through the secondaryairbox 62 rearwards and downwards behind the engine 26 into the throttlebody 68, and from the throttle body 68 into the primary airbox 66 andfinally into the engine 26 via the air inlet 61.

With reference to FIG. 8, the secondary airbox 62 is disposed above theengine 26 and extends partly forward of the engine 26 and the upperstructure 23. The secondary airbox 62 is connected to the throttle body68 by a conduit 69. The conduit 69 extends rearwardly and downwardlyfrom the secondary airbox 62 to the inlet 68 c of the throttle body 68

With reference to FIGS. 8 and 15, the throttle body 68 has a tubularstructure, and extends rearwardly and downwardly from the conduit 69 tothe primary airbox 66. The throttle body 68 is disposed rearwardly ofthe engine cylinder axis 27. The throttle body 68 is disposed rearwardlyand lower than the apex 23 c of the frame upper structure 23. Thethrottle body 68 is disposed below the forwardly extending portion ofthe fuel tank 58. The filler neck 59 of the tank 58 is longitudinallyaligned with the throttle body 68. The throttle body 68 is disposedleftward of the longitudinal centerplane 13 as seen in FIG. 12. Theoutlet 68 b of throttle body 68 is connected to the inlet of the primaryairbox 66 as best seen in FIG. 8.

With reference to FIGS. 8 and 15, the primary air box 66 has a bulbousstructure providing a voluminous chamber for equalizing air pressure ofthe air flow entering the engine 26. The primary airbox 66, is disposedbelow the forwardly extending upper portion of the fuel tank 58. Thelower portion of the fuel tank 58 is disposed just rearward of theprimary airbox 66. As best seen in FIG. 14, the primary airbox 66 isconnected to the air inlet 61 of the engine 26.

With reference to FIGS. 4 to 5C, the throttle body 68 comprises athrottle valve 70. The throttle valve 70 regulates the amount of airflowing through the throttle body 68 entering into the engine 26, whichdetermines in part the mixture of fuel and air burned in each combustioncycle of the engine 26, and thereby the power delivered by the engine26. The throttle valve 70 is a butterfly valve comprising a circulardisc 70 a mounted inside the tubular throttle body 68 that rotates abouta rod 70 b passing diametrically through the disc 70 a. The passage ofair through the tubular throttle body 68 is obstructed by varyingamounts as the disc 70 a rotates about the rod 70 b. The throttle valve70 is in a fully open position (minimal obstruction of air flow) whenthe circular surface of the disc 70 a is at its minimum angle withrespect to the central axis 68 a of the tubular throttle body 68, and ina fully closed position (maximal obstruction of air flow) when thecircular surface of the disc 70 a is at its maximum angle with respectto the central axis 68 a of the tubular throttle body 68.

A throttle valve actuator 74, in the form of an electric motor, isoperatively connected to the disc 70 a to change the position of thedisc 70 a and thereby adjust the opening of the throttle valve 70. Inthe illustrated implementation of the throttle body 68, the throttlevalve 70 and therefore the throttle valve actuator 74 are placedadjacent to the throttle body outlet 68 b which connects to the primaryairbox 66. It is however contemplated that the throttle valve 70 and/orthrottle valve actuator 74 could be places at other positions along thethrottle body 68 between the inlet 68 c and outlet 68 b.

A throttle valve position TVP can be defined in terms of a degree ofopening of the throttle valve 70. The throttle valve position TVP isdefined as a fraction of its fully open position and thus varies from 0%(fully closed) to 100% (fully open). A throttle valve sensor 72 isconnected to the throttle valve 70 to sense the throttle valve positionTVP. In the illustrated implementation, the throttle valve positionsensor 72 is integrated with the actuator 74, but it is contemplatedthat the actuator 74 and sensor 72 could be separate. The throttle valveactuator 72 positions the throttle valve 70 based at least in part on aposition PP of the throttle lever 37 of the snowmobile 10. The actuator74 is controlled based in part on signals received from the ECU 200,which are based on signals received by the ECU 200 from the throttleposition sensor 204, the throttle valve position sensor 72, and otherinput signals such as the engine speed ES and the like.

With reference to FIGS. 7 to 15, the throttle valve actuator 74 attachedto the throttle body 68 is placed between the fuel tank 58 and theengine 26. The throttle valve actuator 74 is disposed below a forwardlyextending portion of the fuel tank 58 containing the filler tube 59. Thethrottle valve actuator 74 is disposed lower than the upper surface ofthe seat 32 in the vertical direction and between the left and rightlateral surfaces of the seat 32 in the lateral direction. The throttlevalve actuator 74 is disposed rearward of a CVT plane 50 a. A portion ofthe throttle valve actuator 74 is disposed longitudinally within aprojection of the circumferential edge of the driven pulley 52 on to thelongitudinal centerplane 13. A portion of the throttle valve actuator 74is also laterally disposed within the projection of the circumferentialedge of the driven pulley 52 on to the longitudinal centerplane 13. Inthe lateral direction, the throttle valve actuator 74 is disposedbetween the longitudinal centerplane 13 and the rear left brace 23 b ofthe frame upper structure 23. The throttle valve actuator 74 is thusdisposed within the pyramidal structure formed by the upper structure23.

With reference to FIGS. 4 and 6, the ECU 200 controls operation of thesnowmobile 10. The ECU 200 receives signals from various sensors inorder to control operation of the snowmobile 10. The ECU 200 sendssignals to various components connected to the engine 26 based on theinformation received from the various sensors in order to control theoperation of the engine 26 and other components of the snowmobile 10.

The throttle operator position sensor 204 senses a position PP of thethrottle operator 44 (finger or thumb actuated throttle lever 44 in theillustrated implementation of the snowmobile 10) and sends a signalrepresentative of the throttle operator position PP to the ECU 200.Depending on the type of throttle operator 44, the throttle operatorposition sensor 204 is generally disposed in proximity to the throttleoperator 37 and senses the movement of the throttle operator 44 or thelinear displacement of a cable connected to the throttle operator 44.

The ECU 200 sends a signal to the throttle valve actuator 74 to adjustthe position TVP of the throttle valve 70, and thereby the air flowthrough the throttle body 68. The throttle valve position TVP isadjusted based in part on the throttle operator position PP as well ason other factors such as the ignition timing IT, required output power Pand torque τ, and the like.

The throttle valve position sensor 72 senses the position (i.e. thedegree of opening) of the throttle valve 70 and sends a signalrepresentative of the position TVP of the throttle valve 70 to the ECU200. The throttle valve position sensor 72 acts as a feedback to the ECU200 since the ECU 200 uses the signal received from the throttle valveposition sensor 72 to determine if the throttle valve actuator 74 hasmoved the throttle valve 37 to the desired position and can makeadjustments accordingly. The throttle valve position sensor 72 can beany suitable type of sensor such as a rheostat, hall-effect sensor,potentiometer, and the like. Depending on the type of throttle valveactuator 74 being used, a separate throttle valve position sensor 72 maynot be necessary. For example, a separate throttle valve position sensor72 would not be required if the throttle valve actuator 74 is a servomotor since servo motors integrate their own feedback circuit thatcorrects the position of the motor and thus have an integrated throttlevalve position sensor 72. In a carbureted engine, the throttle valve 70is located inside the carburetor and the throttle body 68 is replacedwith a carburetor body. For the purposes of the present, the term“throttle body” refers to a carburetor as well as a throttle body.

An engine speed sensor 208 senses the rotational engine speed ES of theoutput shaft 54 of the engine 26 and sends a signal representative ofthe engine speed ES to the ECU 200. The engine speed sensor 208 is ahall-effect type sensor coupled to a trigger wheel on the engine outputshaft 54. It is contemplated that the engine speed sensor 208 could becoupled to any rotating shaft of the engine 26, such as the crankshaft.The rotation speed ES of the engine 26 can be used by the ECU 200 tocalculate the engine torque τ and the power output P of the engine 26.

A vehicle speed sensor 202 senses the speed VS of the snowmobile 10 andsends a signal representative of the speed VS of the snowmobile 10 tothe cluster 48. It is contemplated that the vehicle speed sensor 202could also send a signal representative of the speed VS of thesnowmobile 10 to the ECU 200. The vehicle speed sensor 202 is ahall-effect sensor coupled to a trigger wheel on a driveshaft, such asthe drive axle 55 or a jackshaft of the reduction gear 57 so as to sensea rotational speed thereof. It is contemplated that the vehicle speedsensor 202 could sense a speed of any shaft driven by the driven pulley52 (i.e. any shaft connected between the driven pulley 52 and the track28), including shafts inside the reduction gear 57, to determine thespeed of the snowmobile 10. It is contemplated that any suitable type ofvehicle speed sensor 202 could be used. Alternatively, the vehicle speedsensor 202 could include a global positioning system (GPS unit). Byusing information from the GPS unit, the speed of the vehicle 10 can bedetermined by calculating a change in position of the vehicle 10 over aperiod of time which is normally a function of the GPS unit.

In addition to the throttle valve 70 mentioned above, the ECU 200 isalso connected to the fuel injection system 80 including fuel pumps 86(FIG. 14) and fuel injectors 84 (FIG. 9) for controlling the fuel supplyto the engine 26.

The ECU 200 is connected to the ignition system 82 to control ignitionof the fuel-air mixture in the combustion chamber of the engine 26. Forexample, the ECU 200 controls the ignition timing IT based partly on thethrottle valve position TVP, the throttle operator position PP, and/orengine speed ES. The ECU 200 is also connected to the fuel injectionsystem 80 to control fuel injection into the engine 26.

The ECU 200 is connected to the display cluster 48 to control display ofinformation thereon. The ECU 200 sends signals to the display cluster 48to display information regarding engine speed, vehicle speed, and thelike.

The ECU 200 is connected to the engine cut-off switch 116 to determineif engine operations need to be terminated.

The ECU 200 is connected to the start-up switch 120 to determine whenthe driver desires to commence operation of the engine 26.

The ECU 200 is connected to the security system 130 to verify that thedriver is authorized to operate the snowmobile 10, and to terminatevehicle and/or engine operation in the event of an emergency.

Other sensors (not shown) may also connected to the ECU 200, such as amanifold pressure sensor, an engine coolant temperature sensor, an airflow sensor, an intake air temperature sensor, fuel temperature andpressure sensors, transmission sensor and the like. It is contemplatedthat the ECU 200 could only be connected to some of these components andnot to others. It is also contemplated that the snowmobile 10 could notinclude all of these components. For example, the engine 26 could besupplied with fuel via a carburetor, in which case the snowmobile 10would not include a fuel injector.

It is contemplated that the ECU 200 could be separated into multipleunits each having one or more of the functions described above andfurther below.

The ECU 200 controls operation of the engine 26 based on specificcontrol schemes or map provided to the ECU 200. The control maps provideinformation related to various parameters (such as throttle valveposition, throttle operator position, fuel injection, ignition timing,engine torque, power output, etc.) needed for operation of the engine26. For example, a control map could provide information regarding thevariation of throttle valve position TVP and engine speed ES forachieving a particular power output or engine torque. The ECU 200 mayalso use algorithms, in addition to the control maps, to determine someof the parameters.

As can also be seen in FIG. 6, the engine 26 has a magneto 96. Themagneto 96 is mounted to and driven by the crankshaft of the engine 26.When the magneto 96 rotates with the crankshaft, it generates electricalpower to be supplied to at least the electrical components mentionedabove, including the ECU 200.

With Reference to FIG. 16, a method of starting engine operation willnow be described.

The method 300 is initiated at step 305 when a key 134 is linked to thesecurity system receiver 132. The coupling of the key 134 in the keyreceiver 132 completes a security system circuit 140 when a reed switch138 is closed at step 310.

The method 300 then proceeds when the snowmobile driver activates theengine start-up button 120 at step 315 to indicate a desire to commenceengine operation. In a snowmobile without a starter motor 43, instead ofpushing a start-up button 120, the snowmobile driver pulls a starter 122(FIG. 6) to rotate the flywheel mounted to the crankshaft of the engine26, thereby rotating the crankshaft to begin engine operation.

At step 320, the ECU is activated. The battery 144 is connected to theECU 200 to activate the ECU 200. In the implementation of the snowmobile10, having a starter rope 122 instead of a start-up switch 120, the ECU200 could also be activated by the power generated by the rotation ofthe engine crankshaft as a result of the starter rope 122 being pulled.The activation of the ECU 200 also starts an ECU timer.

The ECU 200 then checks the status of the engine cut-off switch 116 atstep 325. If the engine cut-off switch 116 is determined to bedeactivated, the method 300 proceeds to step 330. If the engine cut-offswitch 116 is determined to be activated, the method 300 remains at step325 until the engine cut-off switch 116 is deactivated.

The ECU 200 checks the reed switch 138 at step 330. If the reed switch138 is determined to be in an “on” or “closed” position (i.e. the key134 is installed properly and the security system circuit 140 iscomplete), the method 300 proceeds to step 335. If at step 330, the reedswitch 138 is determined to be in an “off” or “open” position (i.e. thekey is not installed properly and the security system circuit 140 isincomplete), the method 300 returns to the first step 305. The securitysystem key 134 has to be re-installed so that the method 300 canrecommence from step 305.

It will be understood that the steps 325 and 330 can be performed in thereverse order. In some implementations, the step 330 is omitted sincethe method 300 does not proceed past the step 310 unless the reed switch138 is closed. The reed switch 138 closes (step 310) only if the key 134is installed properly thereby completing the security system circuit140. If the security system circuit 140 is not complete, the battery 144cannot be connected to the ECU 200 or to other systems, and thereforethe ECU 200, the engine 26 and other related systems cannot beactivated. Thus, if the reed switch 138 is not closed and the securitysystem circuit 140 is not complete, pushing the engine start-up button120 would not activate any systems of the snowmobile 10.

If the ECU 200 determines that the engine cut-off switch 116 isdeactivated and the reed switch 138 is closed, at step 335 the ECU 200communicates with the throttle control module 100 to determine if thethrottle operator position PP is set at a position greater than a limit,PP_(limit). The method 300 proceeds to the next step 340 to commenceengine operation only if the throttle operator position PP is eitherless than or equal to the limit position PP_(limit). The throttleoperator position PP could be greater than the limit position PP_(limit)if the throttle lever 44 is being pressed by the snowmobile driver, orif the throttle lever 44 is not at its idle position but stuck at aposition PP greater than the limit position PP_(limit), for some otherreason. If the throttle operator position PP is greater than the limitposition PP_(limit), the method 300 does not allow engine operation tocommence and returns to step 315. The snowmobile operator has to releasethe throttle lever 44 or ensures that the throttle lever 44 is at aposition PP equal to or less than the limit position PP_(limit), beforepressing the start-up button 120 again to recommence the method 300. Itis also contemplated that at step 335, instead of, or in addition tochecking the throttle operator position PP, the ECU could also determinewhether the throttle valve position TVP is above a certain limitposition TVP_(limit). If neither the throttle operator position nor thethrottle valve position TVP is at a position greater than thecorresponding threshold positions, the method 300 would then proceed tostep 340.

If at step 335, the ECU 200 determines that the throttle operatorposition PP is either less than or equal to the limit positionPP_(limit), then at step 340, the ECU 200 allows current from thebattery 144 to flow to the starter motor 43 to rotate the crankshaft forthe combustion process. At step 340, the throttle valve position TVP isallowed to be adjusted based at least in part on the throttle operatorposition PP. It should be understood that the throttle valve actuator 74controls the throttle valve 72 based on the throttle operator positionPP such that the throttle valve position TVP is a function thereof, i.e.TVP=f(PP), not necessarily directly proportional to the throttleoperator position PP. The functional relationship of the throttle valveposition TVP on the throttle operator position PP could depend onfactors such as a mode of operation of the vehicle, and the like. Atstep 340, the ECU 200 also activates other electrical systems connectedto the engine 26 such as the fuel pump 80, the ignition system 82 andthe like. Once the electrical systems connected to the engine 26 areturned on, the method 300 monitors the engine speed ES.

At step 345, if the ECU timer value t is less than a time period T1, themethod proceeds to step 350.

At step 350, if the engine speed ES is determined to be at least equalto a first threshold engine speed ES_(T1), the method 300 proceeds tostep 375. If at step 350, the engine speed ES is determined to be lessthan the first threshold engine speed ES_(T1), the method returns tostep 345. Thus, the method 300 circles between steps 345 and 350 tomonitor the engine speed ES either until the timer value is at leastequal to the time period T1 or the engine speed ES increases above thefirst threshold ES_(T1).

If the ECU timer value is at least equal to T1 at step 345 and theengine speed ES has failed to increase above the first threshold enginespeed ES_(T1), as determined at step 350, the method 300 proceeds tostep 355 to limit the throttle valve position TVP. The ECU 200 sends asignal to the throttle valve actuator 74 to limit the throttle valveexposition TVP to be below a first limit position TVP_(limit1). Thevalue of the first limit throttle valve position TVP_(limit1) is preset.In the illustrated implementation, the first limit throttle valveposition TVP_(limit1) is preset at 0% (closed position of the throttlevalve 70). It is contemplated that the first limit throttle valveposition TVP_(limit1) could be any value between 0 (the closed positionof the throttle valve 70) and 100% (fully opened). From step 355, themethod 300 proceeds to step 360.

At step 360, if the ECU timer value t is less than a time period T2, themethod proceeds to step 365. The time period T2 is greater than the timeperiod T1.

At step 365, the engine speed ES is compared to a second thresholdengine speed ES_(T2). If the engine speed ES is determined to be atleast equal to a second threshold engine speed ES_(T2), the method 300proceeds to step 375. In the illustrated implementation, the secondthreshold engine speed ES_(T2) is set to have to the same value as thefirst threshold engine speed ES_(T1). It is however contemplated thatthe second threshold engine speed ES_(T2) could be smaller than orgreater than the first threshold engine speed ES_(T1).

If at step 365, the engine speed ES is determined to be less than thesecond threshold engine speed ES_(T2), the method returns to step 360.Thus, the method 300 circles between steps 360 and 365 to monitor theengine speed ES either until the ECU timer value t is at least equal tothe time period T2 or the engine speed ES is at least equal to thesecond threshold ES_(T2).

If at step 360, the ECU timer value is at least equal to the second timeperiod T2, the method 300 proceeds to step 370 to place the engine 26 ina “sleep” mode. All the electrical systems including the ECU 200 aredeactivated and disconnect from the battery 144. Engine operation thusfails to commence, and can be restarted again only by reinserting thekey 134 into the key receiver 132 at step 305, or by pushing thestart-up button 120. If the engine speed ES rises to at least the secondthreshold engine speed ES_(T2) (step 365) before the timer value tequals the time period T2 (step 350), the method 300 proceeds to step375.

In the illustrated implementation, the ECU timer is started at step 320when the ECU 200 is powered at step 320. The threshold time periods T1and T2 are defined with respect to this start time. It is howevercontemplated that the timer could be started at a different time, forexample, when the engine speed ES has reached a certain value, or when asystem other than the ECU 200 is activated. It is contemplated that thethreshold time periods T1 and T2 could be defined with respect to anevent other than the timer being started, or the ECU 200 beingactivated.

At step 375, the method 300 determines if the engine speed ES is atleast equal to a transponder threshold engine speed ES_(trans), theengine speed ES at which the engine 26 generates enough power to enablethe transponder 142 to read the identification code of the key 134 andto communicate with the ECU. The method 300 waits at step 375 until theengine speed ES increases to at least the transponder threshold enginespeed ES_(trans) before proceeding to step 380.

At step 380, the identification code of the key 134 is obtained by theECU 200. The transponder 142 reads the identification code contained inthe identification chip of the key 134 linked to the key receiver 132.The ECU 200 transmits an ID request signal to the transponder 142 andreceives a response signal from the transponder 142 which contains theidentification data.

In the illustrated implementation, the transponder threshold enginespeed ES_(trans) is greater than the threshold engine speeds ES_(T1) orES_(T2). It is also contemplated that the transponder threshold enginespeed ES could be less than the threshold engine speeds ES_(T1) orES_(T2). It is contemplated that the identification code of the key 134(step 380) could be read before the engine speed ES has increased to thethreshold engine speeds ES_(T1) or ES_(T2). It is contemplated that thestep 375 could be omitted. For example, the identification code could beread at step 340 when the throttle valve actuator 74 and other systemsof the engine 26 are activated. In this case, the transponder 142 ispowered by the battery 144 for reading the identification chip of thekey 134 and for communication with the ECU 200.

At step 385, the ECU 200 determines whether the installed key 134 isauthorized for operation of the snowmobile 10. It is also contemplatedthat the authorization of the key 134 could be determined by thesecurity system 130 and the result transmitted to the ECU 200. Asmentioned above, the determination of the authorization status of theinstalled key 134 is performed by comparing the decoded identificationdata with one or more authorized identification codes previously storedin an ECU memory (or DESS memory).

If the identification data does not correspond to an authorizedidentification, the ECU 200 determines that the installed key 134 isunauthorized for operation of the snowmobile 10 and proceeds to steps390 and 395 to prevent further operation of the snowmobile 10.

At step 390, the ECU 200 sends a signal to the throttle valve actuator74 to limit the throttle valve position TVP below a security limitedthrottle valve position TVP_(security). In the illustratedimplementation, the security limited throttle valve positionTVP_(security) is contemplated to be less than a throttle valve positionTVP that would produce an engine speed ES that is less than the CVTengagement speed ES_(engage).

At step 395, method 300 prevents engine operation. The engine 26 will bestopped if it has already started. The engine 50 will be prevented fromstarting if it has not already started. The engine 26 is considered tohave started if the engine speed ES is at least enough to sustaincombustion and operation of the engine and related systems (fuelinjection 80, ignition 82, etc.) without being connected to the battery144. The engine speed ES at which the engine is considered to havestarted up is smaller than the engine speed ES_(engage).

Thus, at step 395, if the engine 26 has already started, the ECU 200disconnects the fuel injection system 80, the ignition system 82, thefuel and oil pumps 86 and other electrical systems connected to thebattery 144 and the engine 26 to deactivate these systems. If the engine26 has not yet started, and if one or more of these systems are beingpowered by the battery 144, they will be deactivated by disconnectingthem from the battery 144 in order to prevent draining of the battery144.

It is contemplated that step 395 could be omitted and that if theinstalled key 134 is determined to be unauthorized, the ECU 200 wouldonly limit the throttle valve position to the position TVP_(security)without also preventing engine operation. It is also contemplated that await time could be included between the step 390 and 395. It is furthercontemplated that an indication of authorization failure may bedisplayed to the operator, for example, by flashing an indicator light,or displaying a message on the display cluster 48, or by emitting asound.

If at step 385, the installed key 134 is determined to be authorized,the method 300 proceeds to step 400 to allow further operation of theengine 50. The ECU 200 sends a signal to the throttle valve actuator 74to enable positioning of the throttle valve 70 based on the position ofthe throttle lever 44. Thus, the throttle valve position TVP is allowedto increase beyond the limit position TVP_(limit1) if it was so limitedat step 355.

It is further contemplated that the transponder threshold engine speedES_(trans), be less than the first limit threshold TVP_(limit1), and theidentification code could be read before the step 345. Thus, in someimplementations, the steps 380 to 395 are performed before step 345.

Another implementation of a security system 130′ and method of operatingthe snowmobile will now be described with reference to FIGS. 17, 18 and19. The security system 130′ has some features that are similar to thecorresponding features of the security system 130 described above.Corresponding and similar features of the security systems 130, 130′have been labeled with the same reference numbers and will not bedescribed again herein in detail.

The security system 130′ includes a key receiver 132′ and a key 134′.Similar to the key receiver 132 of FIG. 3A, the key receiver 132′ is inthe form of a metal cylinder positioned in front of the seat 32 on theright side of the upper end of the steering column 42 and below theright side handlebar 37. Similar to the key receiver 132 of FIG. 3A, thekey 134′ is cup-shaped and fits over the key receiver 132. The securitysystem 130′ uses radio frequency identification (RFID) for determiningthe authorization status of a user of the snowmobile 10. The key 134′includes a magnet 146 and an RFID tag 148 including encodedidentification information. The key 134′ can be connected to a lanyard136 as described above. The key receiver 132′ includes an RFID reader150 and a sensor 152 sensitive to the magnetic field of the key magnet146. The sensor 152 is therefore referred to herein as a magnetic sensor152. When the key 134′ is installed on the key receiver 132′, themagnetic field of the key magnet 146 can be sensed by the magneticsensor 152 if the magnetic sensor 150 is powered. When the key 134′ isinstalled on the key receiver 132′, the RFID tag 148 can be read by theRFID reader 150 if the RFID reader is powered.

The key receiver 132′ has a first power connector P1, a first power line156 connected to the first power connector P1, a second power connectorP2, a second power line 158 connected to the second power connector P2,and ground connector 154. Each of the power connectors P1 and P2 isconnected to a power source (not shown) such as a magneto 96 oralternator of the engine 26. The RFID reader 150 is connected to bothpower lines 156 and 158, and thereby to both power connections P1 andP2. The magnetic sensor 152 is connected to the power line 156, andthereby to the power connection P1. The magnetic sensor 152 has aterminal connected to the ground connection 154.

The key receiver 132′ is connected to the ECU 200 for controlling thefunctioning of the RFID reader 150 and the magnetic sensor 152. The ECU200 is also connected to the power connectors P1 and P2 for controllingwhether or not the power connectors P1 and P2 are providing power to thelines 156 and 158 respectively. The power connectors P1 and P2 mayinclude one or more switches and/or other circuit elements for effectingthe control as described below.

In the illustrated implementation, P1 is a power connector that providespower in the power line 156 at a lower voltage than P2, and P2 is apower connector that provides power in the power line 158 at a highervoltage than P1. In the illustrated implementation, P1 provides power upto 5V and P2 provides power at 12V. It is contemplated that the actualvoltage levels of the power provided by the power connections P1 and P2could be different than as disclosed herein and that the voltages mayfluctuate from the given values.

In the illustrated implementation, both of the power connectors P1 andP2 are connected to the same power source, namely the engine 26. In theillustrated implementation, the engine 26 has a magneto 96 and isstarted up manually by pulling a rope 122 attached to the magneto 96. Anexemplary implementation of a manual starting system having a rope to bepulled is shown and described in U.S. Pat. No. 4,422,417, issued Dec.27, 1983, the entirety of which is incorporated herein by reference. Themagneto 96 generates power as it turns in response to the pull of therope 122. The rope 122 can be pulled repeatedly in order to continuepower generation by the magneto 96. The power generated each time therope 122 is pulled depends on the force with which the rope 122 ispulled—the greater the pulling force on the rope 122, the greater thepower generated. The voltage of the power obtained from the magneto 96while the rope 122 is being pulled is lower than that obtained if theengine 26 was provided with a battery and an electric starter motor 43.The voltage of the power generated by the engine 26 is also lower duringmanual start-up of the engine 26 than when the engine 26 is operating athigher engine speeds (1200 RPM, for example) after start-up. The ECU 200controls the power connector P1 such that P1 is active during the startup procedure, i.e. while the rope 122 is being pulled for a manualstart-up of the engine 26. Thus the power line 156 provides low voltagepower during start-up of the engine 26. The ECU 200 controls the powerconnector P2 such that P2 is active after the engine 26 has started upand when the engine 26 has achieved operational engine speeds (i.e. theengine 26 is capable of sustaining its momentum). In other words, thepower line 158 provides high voltage power after the engine started up.In some implementations, the power line 158 delivers power when theengine speed is above a threshold engine speed.

The magnetic sensor 152 is a low power sensor in the form of a halleffect sensor. The hall effect sensor 152 senses the magnetic field ofthe key magnet 146 when the key 134′ is brought in proximity to the keyreceiver 132′. The low power hall effect sensor 152 can be operatedusing the low voltage power generated by the magneto 96 when it isstarting up as a result of rope-starting of the engine 26. In theillustrated implementation of FIGS. 16 and 17, the key 134′ is installedin the key receiver 132′ before pulling on the rope 122 connected to themagneto 96 for starting up the engine 26. While it is desirable toprevent the engine 26 from starting up unless the key 134′ is installedin the key receiver 132′, it is undesirable for the operator of thesnowmobile 10 to have to pull the rope 122 repeatedly in order tostart-up the engine 26. The low power sensor hall effect sensor 152enables the detection of the key 134′ within one rope-start attempt. Thepower requirement of the sensor 152 is also low enough to permitpowering of the ECU 200 to initiate other procedures for starting thecombustion cycle of the engine 26 with the energy obtained from a singlepull of the rope 122, as will be described below.

Although the present description is being provided with reference to alow power sensor 152 in the form of a magnetic sensor, specifically ahall effect sensor, it should be understood that other kinds of lowpower magnetic and non-magnetic sensors are also contemplated. The keymagnet 146 could be a magnetic element which is sensitive to a magneticfield without being a magnet, and the sensor 152 could be magneticsensor 152 other than a hall effect sensor which is configured to detectthe presence of the magnetic element. The sensor 152 could also be asensor operating under a principle other than magnetism, in which casethe key magnet 146 of the key 134′ would be replaced with an elementassociated with the type of sensor being used.

With reference to FIGS. 17, 18 and 19, another implementation of amethod 400 of controlling operation of the snowmobile 10 will bedescribed. The method 400 is described below with reference to a manualstart-up of the engine 26 but it should be understood that aspects ofthe method 44 are also applicable to an electronic or battery assistedstart-up of the engine 26.

The method 400 is commenced at step 410 by pulling the rope 122connected to the magneto 96. The ECU 200 is activated as soon as therope 122 is pulled. In addition, when the rope 122 connected to themagneto 96 is pulled, power generated by the engine 26 (i.e. magneto 96)is delivered via the power line 156 to the sensor 152.

Power in the power line 156 is represented by the signal 162 in FIG. 18.As can be seen in FIG. 18, the voltage of the power line 156 increaseswith time (assuming that the rope 122 is pulled at time t=0) until itreaches a voltage level V_(low) at time t₁. V_(low) is the voltage levelat which the sensor 152 can be operated. As mentioned above, V_(low) is5V in the illustrated implementation, but it is contemplated thatV_(low) could be more or less than 5V. The power line 156 continues todeliver power at the voltage V_(low) unless the engine 26 start-upprocedure fails due to reasons described below. If the engine 26 issuccessfully started up, power line 156 continues to deliver power atthe voltage V_(low) until the operation of the engine 26 is terminated,or unless the key 134′ is removed from the key receiver 132′.

At step 420, the sensor 152 is activated at time t₂ which is after thevoltage level of the power line 156 reaches a V_(low) at time t₁. Thesensor 152, when activated, detects the presence or absence of the keycard 134′. The sensor 152 sends a signal 164 (FIG. 18) to the ECU 200indicative of the presence or absence of the key 134′. The signal 164has a non-zero voltage as long as a key 134′ is detected by the sensor152′.

At step 430, if the ECU 200 determines that the key 134′ has not beendetected by the sensor 152, the method 400 proceeds to step 435 wherestart up of the engine 26 is terminated. At step 430, if the key 134′ isdetermined to have been detected by the sensor 152, the ECU 200 proceedsto step 440 in order to continue the engine start-up procedure.

At step 440, the ECU 200 begins powering other components, such as thefuel pump, fuel injection and ignition systems 80, 82, in order toachieve combustion in the engine 26. The power delivered to the fuelpump is represented by the signal 166 in FIG. 18. The power delivered tothe fuel injector is represented by the signal 168 in FIG. 18. The powerdelivered to the ignition system is represented by the signal 170 inFIG. 18.

First, the fuel pump is activated. As can be seen in FIG. 18, the signal166 to the fuel pump comprises a single initial pulse starting at timet₃ followed by a constant uniform voltage signal starting at a time t₆.After time t₆, the fuel pump receives power constantly for continuousoperation of the fuel pump. Continuous operation of the fuel pumprequires more power than that generated by a single pull of the rope 122connected to the magneto 96. Pulsed operation of the fuel pump uses asmaller amount of power than a continuously operating fuel pump. Thefuel pump is therefore initially powered by a voltage pulse. The voltagepulse for initial operation of the fuel pump is of a magnitude(V_(fpump)) and a duration to sufficiently pressurize the fuel lines toenable at least one fuel injection cycle of the fuel injector. Theduration of the pulse of the fuel pump signal 166 is 10 milliseconds inthe illustrated implementation but it is contemplated that the pulsewidth of fuel pump signal 166 could be other than 10 milliseconds. It isalso contemplated that the magnitude of the fuel pump signal 166 couldbe different than illustrated.

Once the fuel lines (not shown) are pressurized as a result of thevoltage pulse delivered to the fuel pump at time t₃, the fuel injectoris powered at time t₄ in order to inject fuel from the fuel lines in tothe combustion chamber f the engine 26. The power 168 is delivered tothe fuel injector in the form of pulses at a regular frequency. Eachpulses of the signal 168 causes a predetermined amount of fuel to beinjected into the combustion chamber for ignition. The ECU 200 accessescontrol maps to determine the predetermined amount of fuel. The amountof fuel injected for each pulse of the fuel injector signal 168 is basedin part on parameters such as the current engine speed ES, the ambienttemperature, the temperature of the engine coolant, and the like. Themagnitude and width of the fuel injector signal 168 pulse is determinedbased on the amount of time and power needed to inject the predeterminedamount of fuel. The ignition system is then sent a short voltage pulse(see signal 170 in FIG. 18) after each pulse of the signal 168 to createa spark across a spark plug of the ignition system. The time intervalbetween a pulse of the fuel injection signal 168 and a correspondingpulse of the ignition signal 170 is predetermined based on the physicalcharacteristic of the particular engine 26 and the desired performancecharacteristics of the engine 26.

With reference to FIG. 18, at time t₆, the engine 26 achieves continuouscombustion. The fuel pump is continuously powered, and the fuel injectorpulses (signal 168) and the ignition system pulses (signal 170) aredelivered at a higher frequency than prior to the time t₆. If continuouscombustion is not reached in response to a single pull of the rope 122,the rope 122 of the magneto 96 may be pulled again in order to generateadditional power for achieving continuous combustion.

Depending on the speed with which the rope 122 is pulled, and thereforethe total power generated by the magneto 96, a second cycle of fuelinjection and ignition could be attempted before the rope 122 needs tobe pulled again. If the speed with which the rope 122 is pulled, or theamount of rope 122 pulled, is not sufficient to generate enough powerfor a second cycle of fuel injection and ignition, the rope 122 willhave to be pulled a second time in order to have a second cycle of fuelinjection and ignition. It should be understood that the amount of timeavailable for fuel injection and ignition cycles for starting up theengine 26 depends partly on the amount of time taken to execute step420. If the step 420 where the sensor 150 is activated and the key 154′is detected does not occur quickly enough after the rope 122 is pulled,then there will not be sufficient time to follow up with the fuelinjection and ignition cycles for starting up the engine 26. In theillustrated implementation, the ECU 200 determines that a key 134′ hasbeen detected by the sensor 152 within 100 milliseconds after the rope122 has been pulled which corresponds to 25% of the full length of therope 122 having been pulled which leaves enough time and generatesenough power for activating other components of the engine 26.

With reference to FIG. 18, a signal 172 is shown which represents thepower used for operation of all of the components such as the fuelpumps, fuel injectors, ignition systems and the like. After the rope 122of the magneto 96 is pulled, the power used for operation of the variouscomponents increases with time at first, and then remains constant. Inthe implementation illustrated in FIGS. 17 and 18, the voltage level ofthis constant power is 55V. It is however contemplated that the voltagelevel of this contact power could be other than 55 volts.

At step 450, the method 400 determines if the engine speed ES is atleast equal to a reader threshold engine speed ES_(reader). When theengine speed ES is at least equal to the reader threshold engine speedES_(reader), the magneto 96 is able to generate enough power to enablethe RFID reader 150 to read the identification code of the RFID tag 148.The method 400 waits at step 450 until the engine speed ES increases toat least the reader threshold engine speed ES_(reader) before proceedingto step 460. In the illustrated implementation, the reader thresholdengine speed ES_(reader) is 1200 rpm and the RFID reader is powered by a12V signal. It is contemplated that the reader threshold engine speedES_(reader) could be greater or smaller than 1200 rpm depending on theparticular configuration of the engine 26 and the RFID reader 150. It isalso contemplated that the RFID reader 150 could be powered by a voltageother than 12V. The reader threshold engine speed ES_(reader) is lowerthan a CVT engagement speed ES_(engage). As will be understood from thediscussion above, the reader threshold engine speed ES_(reader) isgreater than the engine speed ES at which the sensor 152 is activated.Once the ECU 200 determines that the engine speed ES is at least equalto the reader threshold engine speed ES_(reader), the method proceeds tostep 460, where the RFID reader 150 is powered by the power connectionP2 via the line 158.

With reference to FIG. 18, signal 160 represents the voltage of thepower line 158 which powers the RFID reader 150. The RFID reader 150 isinitiated at a time t₇ which is later than all the other signals 162,164, 166, 168, 170 to ensure that the power requirements for operationof all the components do not exceed the power generated by the pullingof the rope 122 connected to the magneto 96. If the reader 150 wasinitiated at an earlier time, some of the components of the engine 26may not be sufficiently powered to achieve continuous combustion withina single pull of the rope.

At step 460, the RFID reader 150 is activated and reads the RFID tag 148of the key 134′ to determine if the key 134′ is an authorized key.

At step 470, the ECU 200 determines whether the installed key 134′ isauthorized for operation of the snowmobile 10. It is also contemplatedthat the authorization of the key 134′ could be determined by the RFIDreader 150 and the result transmitted to the ECU 200. As mentionedabove, the determination of the authorization status of the installedkey 134′ is performed by comparing the decoded identification data withone or more authorized identification codes previously stored in amemory of the ECU 200. If the key 134′ is determined to be authorizedfor operation of the snowmobile 10, the method 400 proceeds to step 480to continue operation of the engine 26 based on the requests of theoperator of the snowmobile 10. If the key 134′ is determined to beunauthorized for operation of the snowmobile 10, the method proceeds tostep 490.

At step 480, the ECU 200 allows operation of the engine 26 based atleast in part on the operators demands. The ECU 200 accesses controlmaps for the particular mode of operation and the authorization of theparticular operator in order to control operation of the engine 26.

At step 490, the start-up procedure of the engine 26 is terminated andthe operation of the engine 26 is limited to a security limited enginespeed. In the present implementation, the security limited engine speedis an engine speed ES that is lower than the CVT engagement speedES_(engage). Since the engine speed ES is limited to be lower than theCVT engagement speed ES_(engage), the CVT 50 does not transmit thetorque generated by the engine 26 and the snowmobile 10 is not beingpropelled forward. It is contemplated that the engine 26 couldautomatically turn off after a certain period of time following step490, unless an authorized key 134′ is provided.

Modifications and improvements to the above-described implementations ofthe present technology may become apparent to those skilled in the art.The foregoing description is intended to be exemplary rather thanlimiting. The scope of the present technology is therefore intended tobe limited solely by the scope of the appended claims.

What is claimed is:
 1. A method of operating a vehicle, the vehiclecomprising: an engine; an engine control unit (ECU) controllingoperation of the engine; a throttle operator operatively connected tothe ECU; a throttle body fluidly communicating with the engine; athrottle valve disposed in the throttle body regulating fluid flow tothe engine; a throttle valve actuator connected to the throttle valvefor controlling a throttle valve position, the throttle valve actuatorbeing in electronic communication with the ECU; and a key receiverconfigured to link to a key, the method comprising: linking a key to thekey receiver; initiating engine operation; if the key is linked to thekey receiver and engine operation has been initiated: reading anidentification code of the key and thereby determining an authorizationstatus of the key; if the key is determined to be an authorized key,controlling the throttle valve position based in part on a throttleoperator position; and if the key is determined to be an unauthorizedkey, limiting the throttle valve position to be less than a securitylimited throttle valve position.
 2. The method of claim 1, wherein thesecurity limited throttle valve position is less than a CVT engagementposition of the throttle valve.
 3. The method of claim 1, wherein thestep of reading the digitally encoded identification of the digitallyencoded key occurs when an engine speed is greater than a transponderthreshold engine speed, the transponder threshold engine speed beingless than a CVT engagement speed.
 4. The method of claim 1, wherein thevehicle further comprises an engine cut-off switch, the method furthercomprising preventing engine operation if the engine cut-off switch isactivated.
 5. The method of claim 1, wherein the vehicle furthercomprises a switch electrically connected to the key receiver, theswitch being a reed switch, the method further comprising: closing theswitch when a key is coupled to the key receiver; and preventing engineoperation if the switch is not closed.
 6. The method of claim 1, furthercomprising: determining one of the throttle operator position and thethrottle valve position; and preventing connection between a battery anda starter motor if the one of the throttle operator position and thethrottle valve position is greater than the corresponding one of athrottle operator limit position or a throttle valve position limit. 7.A method of operating a vehicle, the vehicle comprising: an engine forgenerating electrical power; an engine control unit (ECU) operativelyconnected to the engine for controlling operation of the engine; athrottle operator operatively connected to the ECU; a throttle bodyfluidly communicating with the engine; a throttle valve disposed in thethrottle body regulating fluid flow to the engine; and a key receiverconnected to the ECU and configured to receive a digitally encoded key,the method comprising: installing a digitally encoded key to the keyreceiver; detecting a presence of the key without reading anidentification code of the key; providing an electrical power to the keyreceiver; and reading an identification code of the key with the keyreceiver responsive to the key receiver receiving the electrical power.8. The method of claim 7, wherein: the key receiver is configured toreceive power only if the key is installed thereto; and detecting of thepresence of the key is achieved by determining that the key receiver hasreceived power.
 9. The method of claim 7, wherein: the key receivercomprises a sensor and a reader; the electrical power comprises a firstelectrical power and a second electrical power, the second electricalpower being greater than the first electrical power; the presence of thekey is detected by the sensor without reading the identification code ofthe key and responsive to the sensor receiving the first electricalpower; and the identification code of the key is read by the readerresponsive to the reader receiving the second electrical power.
 10. Themethod of claim 9, wherein: the key comprises a magnetic member; and thesensor comprises a hall effect sensor configured to sense a magneticfield of the magnetic member for detecting the presence of the key. 11.The method of claim 10, wherein: the key comprises an RFID tag; and thereader comprises an RFID reader configured to obtain the identificationcode of the key via radiofrequency communication with the RFID tag. 12.The method of claim 9, wherein the engine further comprises: acrankshaft, the engine generating power when the crankshaft rotates; amagneto connected to the crankshaft for rotation therewith; and a ropeconnected to the crankshaft for manual start up of the engine, thecrankshaft and the magneto being rotated by the rope when pulling on therope, the method further comprising: generating the first electricalpower by pulling the rope to rotate the crankshaft and the magneto; andproviding, to the sensor, the first electrical power generated by theengine as a result of the pulling of the rope.
 13. The method of claim12, wherein the snowmobile further comprises: a fuel injection systemfluidly connected to the engine; and an ignition system connected to theengine, the method further comprising, before providing the secondelectrical power to the reader: operating the fuel injection system toinject fuel into the engine; operating the ignition system to ignite thefuel injected into the engine; and increasing a rotational speed of thecrankshaft responsive to the igniting of the fuel injected into theengine.
 14. The method of claim 13, wherein the identification code ofthe key is read by the reader responsive to the rotational speed of thecrankshaft being greater than a reader threshold engine speed.
 15. Themethod of claim 14, wherein: the snowmobile comprises a CVT operativelyconnected to the crankshaft; and the reader threshold engine speed issmaller than a CVT engagement speed.
 16. The method of claim 15, furthercomprising: determining an authorization status of the readidentification code of the key; and responsive to the identificationcode of the key being determined to have an authorized status,controlling the throttle valve position based at least in part on athrottle operator position.
 17. The method of claim 16, furthercomprising: responsive to the identification code of the key beingdetermined to have an unauthorized status, limiting the engine speed toa security limited engine speed.
 18. The method of claim 17, wherein thesecurity limited engine speed is lower than the CVT engagement speed.19. The method of claim 14, wherein the rope is pulled only once priorto reading the identification code of the key.